Xiaozhou Jiang | PubMed Health

PubMed2006

Genetic profiling of dendritic cells exposed to live- or ultraviolet-irradiated Chlamydia muridarum reveals marked differences in CXC chemokine profiles.

Chlamydia trachomatis is a major cause of sexually transmitted disease worldwide for which an effective vaccine is being actively pursued. Current vaccine efforts will be aided by elucidating the interaction between Chlamydia and dendritic cells (DCs). Protective immunity appears to develop slowly following natural infection in humans, and early vaccine trials using inactivated C. trachomatis resulted in partial, short-lived protection with possible enhanced inflammatory pathology during re-infection. Thus, immunity following natural infection with live chlamydia may differ fundamentally from immune responses induced by immunization with inactivated chlamydia. We explored this conjecture by studying the response of DCs exposed to either viable or inactivated [ultraviolet (UV) -irradiated] chlamydia elementary bodies (EBs; designated as Live-EB and UV-EB, respectively) using Affymetrix GeneChip microarrays. Thirty-one immunologically characterized genes were differentially expressed by DCs following exposure to Live-EB or UV-EB, including two glutamic acid-leucine-arginine cysteine-X-cysteine (ELR CXC) neutrophil chemoattractant chemokines, Cxcl1 (KC), and Cxcl2 (MIP-2). Up-regulation of these genes by Live-EB as compared to UV-EB was verified by quantitative reverse transcription-polymerase chain reaction and increased chemokine secretion was confirmed by enzyme-linked immunosorbent assay both in vitro and in vivo. Immunofluorescence and fluorescence-activated cell sorter analysis of chlamydia-infected lung tissue confirmed that Live-EB but not UV-EB induced significant DC and neutrophil infiltration during infection. These observations demonstrate that the development of an antichlamydial immune response is dramatically influenced by chlamydial viability. This has implications as to why early inactivated chlamydial vaccines were ineffective and suggests that new vaccine design efforts may benefit from in vitro DC screening for ELR chemokine expression profiles.

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PubMed2003

Modulation of mThy28 nuclear protein expression during thymocyte development.

We have recently shown that down-regulation of mouse Thy28 (mThy28) protein expression appears to be accompanied by apoptotic processes. Thymocytes from mice contain moderate amounts of mThy28 protein and undergo proliferation, differentiation, or apoptosis during murine thymic maturation. As a first step to examine the potential role of the mThy28 protein in the thymocyte development, such as positive-negative selection, the expression of mThy28 protein in the thymocyte subsets was examined. Thymocytes are separated into four subpopulations by the expression levels of CD4 and CD8: CD4-CD8- (DN), CD4+CD8+ (DP), and CD4+CD8- or CD4-CD8+ (SP). Flow cytometry analysis using three-color staining demonstrated that the mThy28 expression in immature DP cells is lower than that in DN and SP cells. The down-regulation of the mThy28 expression in the DP stage was also detected by Western blotting and reverse transcription-polymerase chain reaction (RT-PCR). The immunostaining method also showed that mThy28 protein was expressed in the medulla containing mature thymocytes, but not the cortex having immature thymocytes. The mThy28 protein in the thymocytes was mainly localized in the nucleus, as recently demonstrated in lymphoma cells, indicating that the mThy28 protein resides in the nucleus, irrespective of the cyclic or resting stage of the cell cycle. Together, the observation that mThy28 expression is down-modulated during the DP stage suggests that mThy28 protein might play some role in the positive-negative selection step in thymic maturation.

Animals↗